EM Waves and Their Uses Flashcards
How is infrared useful?
Used in wireless remote controllers.
They work by emitting different patterns of infra-red waves to send different commands to an appliance.Optical fibres carry data over long distnaces very quickly. - infrared and visible light
How do optical fibres work.
The signal is carried as pulses of light are infrared radiation and is reflected off the sides of a very narrow core from one end of the fibre to the other.
How do cameras work?
They use a lens to focus visible light onto a light sensitive film or electronic sensor.
The lens aperture controls how much light enters the camera.
The shutter speed determines how long the film or sensor is exposed to light.
What happens when you vary the aperture and shutter speed and also the sensitivity of the film or the sensor?
A photographer can capture as much or as little as they want in their photograph.
What does communication to and from satellites use?
Microwaves.
You need to use a microwave which can pass easily through the EARTH’s watery atmosphere.
Radio waves can’t do this.
Satellite TV.
The signal from a transmitter is transmitted into space
where it is picked up by the satellites receiver dish orbiting thousands of kilometeres above the Earth.
The satelittes transmits the signal back to Earth in a different direction where its received by a satellite dish on the ground.
Mobile phones.
Also travel as microwaves between your phone and the nearest transmitter.
Some wavelengths of microwaves ate absorbed by water molecules and heat the, up.
If the water in question happens to be in your cells you might start to cook.
Living near a mast.
Damage your health however isn’t conclusive evidence either way.
Microwaves are used by remote sensing satelittes to do what?
To ‘see’ through the clouds and monitor oil spills track the movement of icebergs, see how much rainforest has been chopped down.
